[L4D] Addon Help: Fairview campaign

So recently I've been makin' a compilation campaign of No Mercy-Crash Course-Death Toll, because I can. Encountered lots of problems and errors along the way, but I got rid of most of the big ones.

This one that just cropped is huge, however, especially because I can't test for it on my own local computer.

Problem: The addon installs and runs fine for me and one other person, but for two others so far it does not. They can both see the addon as "sort of" recognized by the game, as it is in the list of addons found in Extras -> Addons. However, neither can create a game with this addon, nor can they connect to a lobby with this addon. The game simply tells them that they don't have the addon installed.

Download link:
http://rapidshare.com/files/29850793...ew_1.1.7z.html

I would very much appreciate a few people downloading and installing this, and posting back here with the results. Or if you're a knowledgeable chap with some experience doing this, perhaps you can take a stab at what exactly I fucked up.